Prioritizing read locations based on an error history

ABSTRACT

A computing device includes an interface configured to interface and communicate with a dispersed storage network (DSN), a memory that stores operational instructions, and processing circuitry. The processing circuitry is configured to execute the operational instructions to perform various operations and functions. The computing device identifies slice error(s) associated with first storage unit(s) (SU(s)) of a first storage set that distributedly store a set of encoded data slices (EDSs) and second SU(s) of a second storage set. The computing device determines usage priority level(s) of the first SU(s) or the second SU(s) based on the slice error(s) and produces a selected storage set from the first SU(s) and the second SU(s) based on a more favorable usage priority level of the usage priority level(s) and facilitates execution of data access to at least the decode threshold number of EDSs based on the selected storage set.

CROSS REFERENCE TO RELATED PATENTS

The present U.S. Utility patent application also claims priority pursuant to 35 U.S.C. § 120, as a continuation-in-part (CIP) of U.S. Utility patent application Ser. No. 15/673,978, entitled “STORING DATA IN A DISPERSED STORAGE NETWORK,” filed Aug. 10, 2017, pending, which claims priority pursuant to 35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No. 14/876,154, entitled “STORING DATA IN A DISPERSED STORAGE NETWORK,” filed Oct. 6, 2015, issued as U.S. Pat. No. 9,774,684 on Sep. 26, 2017, which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/086,611, entitled “MAINTAINING DATA INTEGRITY IN A DISPERSED STORAGE NETWORK” filed Dec. 2, 2014, all of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes.

U.S. Utility application Ser. No. 14/876,154 also claims priority pursuant to 35 U.S.C. § 120 as a continuation-in-part (CIP) of U.S. Utility application Ser. No. 14/792,577, entitled “DISPERSED STORAGE WRITE PROCESS,” filed Jul. 6, 2015, issued as U.S. Pat. No. 9,354,974 on May 31, 2016, which is a continuation of U.S. Utility application Ser. No. 13/863,475, entitled “DISPERSED STORAGE WRITE PROCESS,” filed Apr. 16, 2013, issued as U.S. Pat. No. 9,092,140 on Jul. 28, 2015, which is a continuation of U.S. Utility application Ser. No. 12/797,025, entitled “DISPERSED STORAGE WRITE PROCESS,” filed Jun. 9, 2010, issued as U.S. Pat. No. 8,595,435 on Nov. 26, 2013, which claims priority pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Application No. 61/230,038, entitled “DISPERSED STORAGE NETWORK VERSION SYNCHRONIZATION,” filed Jul. 30, 2009, all of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes.

U.S. Utility application Ser. No. 13/863,475 also claims priority pursuant to 35 U.S.C. § 120 as a continuation-in-part (CIP) patent application of U.S. Utility application Ser. No. 12/080,042, entitled, “REBUILDING DATA ON A DISPERSED STORAGE NETWORK,” filed Mar. 31, 2008, issued as U.S. Pat. No. 8,880,799 on Nov. 4, 2014, which is a continuation-in-part (CIP) of U.S. Utility application Ser. No. 11/973,542, entitled “ENSURING DATA INTEGRITY ON A DISPERSED STORAGE GRID,” filed Oct. 9, 2007; and is a continuation-in-part (CIP) of U.S. Utility application Ser. No. 11/403,391, entitled “SYSTEM FOR REBUILDING DISPERSED DATA,” filed Apr. 13, 2006, issued as U.S. Pat. No. 7,546,427 on Jun. 9, 2009, which is a continuation-in-part (CIP) of U.S. Utility application Ser. No. 11/241,555, entitled “SYSTEMS, METHODS, AND APPARATUS FOR SUBDIVIDING DATA FOR STORAGE IN A DISPERSED DATA STORAGE GRID,” filed Sep. 30, 2005, issued as U.S. Pat. No. 7,953,937 on May 31, 2011, all of which are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to computer networks and more particularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/or store data. Such computing devices range from wireless smart phones, laptops, tablets, personal computers (PC), work stations, and video game devices, to data centers that support millions of web searches, stock trades, or on-line purchases every day. In general, a computing device includes a central processing unit (CPU), a memory system, user input/output interfaces, peripheral device interfaces, and an interconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using “cloud computing” to perform one or more computing functions (e.g., a service, an application, an algorithm, an arithmetic logic function, etc.) on behalf of the computer. Further, for large services, applications, and/or functions, cloud computing may be performed by multiple cloud computing resources in a distributed manner to improve the response time for completion of the service, application, and/or function. For example, Hadoop is an open source software framework that supports distributed applications enabling application execution by thousands of computers.

In addition to cloud computing, a computer may use “cloud storage” as part of its memory system. As is known, cloud storage enables a user, via its computer, to store files, applications, etc. on an Internet storage system. The Internet storage system may include a RAID (redundant array of independent disks) system and/or a dispersed storage system that uses an error correction scheme to encode data for storage.

Prior art data storage systems do not have acceptable means by which error-affected devices or components may be appropriately handled without adversely affecting the overall system performance. There exists a need in the art for improved ways to operate data storage systems operate including to mitigate or eliminate the adverse effects caused by error-affected devices or components.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed or distributed storage network (DSN) in accordance with the present invention;

FIG. 2 is a schematic block diagram of an embodiment of a computing core in accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storage error encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an error encoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an error encoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of an encoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storage error decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an error decoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of another embodiment of a dispersed or distributed storage network (DSN) in accordance with the present invention;

FIG. 10 is a flowchart illustrating an example of storing data in accordance with the present invention; and

FIG. 11 is a diagram illustrating an embodiment of a method for execution by one or more computing devices in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, or distributed, storage network (DSN) 10 that includes a plurality of computing devices 12-16, a managing unit 18, an integrity processing unit 20, and a DSN memory 22. The components of the DSN 10 are coupled to a network 24, which may include one or more wireless and/or wire lined communication systems; one or more non-public intranet systems and/or public internet systems; and/or one or more local area networks (LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may be located at geographically different sites (e.g., one in Chicago, one in Milwaukee, etc.), at a common site, or a combination thereof. For example, if the DSN memory 22 includes eight storage units 36, each storage unit is located at a different site. As another example, if the DSN memory 22 includes eight storage units 36, all eight storage units are located at the same site. As yet another example, if the DSN memory 22 includes eight storage units 36, a first pair of storage units are at a first common site, a second pair of storage units are at a second common site, a third pair of storage units are at a third common site, and a fourth pair of storage units are at a fourth common site. Note that a DSN memory 22 may include more or less than eight storage units 36. Further note that each storage unit 36 includes a computing core (as shown in FIG. 2, or components thereof) and a plurality of memory devices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and the integrity processing unit 20 include a computing core 26, which includes network interfaces 30-33. Computing devices 12-16 may each be a portable computing device and/or a fixed computing device. A portable computing device may be a social networking device, a gaming device, a cell phone, a smart phone, a digital assistant, a digital music player, a digital video player, a laptop computer, a handheld computer, a tablet, a video game controller, and/or any other portable device that includes a computing core. A fixed computing device may be a computer (PC), a computer server, a cable set-top box, a satellite receiver, a television set, a printer, a fax machine, home entertainment equipment, a video game console, and/or any type of home or office computing equipment. Note that each of the managing unit 18 and the integrity processing unit 20 may be separate computing devices, may be a common computing device, and/or may be integrated into one or more of the computing devices 12-16 and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to support one or more communication links via the network 24 indirectly and/or directly. For example, interface 30 supports a communication link (e.g., wired, wireless, direct, via a LAN, via the network 24, etc.) between computing devices 14 and 16. As another example, interface 32 supports communication links (e.g., a wired connection, a wireless connection, a LAN connection, and/or any other type of connection to/from the network 24) between computing devices 12 & 16 and the DSN memory 22. As yet another example, interface 33 supports a communication link for each of the managing unit 18 and the integrity processing unit 20 to the network 24.

Computing devices 12 and 16 include a dispersed storage (DS) client module 34, which enables the computing device to dispersed storage error encode and decode data as subsequently described with reference to one or more of FIGS. 3-8. In this example embodiment, computing device 16 functions as a dispersed storage processing agent for computing device 14. In this role, computing device 16 dispersed storage error encodes and decodes data on behalf of computing device 14. With the use of dispersed storage error encoding and decoding, the DSN 10 is tolerant of a significant number of storage unit failures (the number of failures is based on parameters of the dispersed storage error encoding function) without loss of data and without the need for a redundant or backup copies of the data. Further, the DSN 10 stores data for an indefinite period of time without data loss and in a secure manner (e.g., the system is very resistant to unauthorized attempts at accessing the data).

In operation, the managing unit 18 performs DS management services. For example, the managing unit 18 establishes distributed data storage parameters (e.g., vault creation, distributed storage parameters, security parameters, billing information, user profile information, etc.) for computing devices 12-14 individually or as part of a group of user devices. As a specific example, the managing unit 18 coordinates creation of a vault (e.g., a virtual memory block associated with a portion of an overall namespace of the DSN) within the DSN memory 22 for a user device, a group of devices, or for public access and establishes per vault dispersed storage (DS) error encoding parameters for a vault. The managing unit 18 facilitates storage of DS error encoding parameters for each vault by updating registry information of the DSN 10, where the registry information may be stored in the DSN memory 22, a computing device 12-16, the managing unit 18, and/or the integrity processing unit 20.

The DSN managing unit 18 creates and stores user profile information (e.g., an access control list (ACL)) in local memory and/or within memory of the DSN module 22. The user profile information includes authentication information, permissions, and/or the security parameters. The security parameters may include encryption/decryption scheme, one or more encryption keys, key generation scheme, and/or data encoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particular user, a user group, a vault access, public vault access, etc. For instance, the DSN managing unit 18 tracks the number of times a user accesses a non-public vault and/or public vaults, which can be used to generate a per-access billing information. In another instance, the DSN managing unit 18 tracks the amount of data stored and/or retrieved by a user device and/or a user group, which can be used to generate a per-data-amount billing information.

As another example, the managing unit 18 performs network operations, network administration, and/or network maintenance. Network operations includes authenticating user data allocation requests (e.g., read and/or write requests), managing creation of vaults, establishing authentication credentials for user devices, adding/deleting components (e.g., user devices, storage units, and/or computing devices with a DS client module 34) to/from the DSN 10, and/or establishing authentication credentials for the storage units 36. Network administration includes monitoring devices and/or units for failures, maintaining vault information, determining device and/or unit activation status, determining device and/or unit loading, and/or determining any other system level operation that affects the performance level of the DSN 10. Network maintenance includes facilitating replacing, upgrading, repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missing encoded data slices. At a high level, the integrity processing unit 20 performs rebuilding by periodically attempting to retrieve/list encoded data slices, and/or slice names of the encoded data slices, from the DSN memory 22. For retrieved encoded slices, they are checked for errors due to data corruption, outdated version, etc. If a slice includes an error, it is flagged as a ‘bad’ slice. For encoded data slices that were not received and/or not listed, they are flagged as missing slices. Bad and/or missing slices are subsequently rebuilt using other retrieved encoded data slices that are deemed to be good slices to produce rebuilt slices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core 26 that includes a processing module 50, a memory controller 52, main memory 54, a video graphics processing unit 55, an input/output (IO) controller 56, a peripheral component interconnect (PCI) interface 58, an IO interface module 60, at least one IO device interface module 62, a read only memory (ROM) basic input output system (BIOS) 64, and one or more memory interface modules. The one or more memory interface module(s) includes one or more of a universal serial bus (USB) interface module 66, a host bus adapter (HBA) interface module 68, a network interface module 70, a flash interface module 72, a hard drive interface module 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operating system (OS) file system interface (e.g., network file system (NFS), flash file system (FFS), disk file system (DFS), file transfer protocol (FTP), web-based distributed authoring and versioning (WebDAV), etc.) and/or a block memory interface (e.g., small computer system interface (SCSI), internet small computer system interface (iSCSI), etc.). The DSN interface module 76 and/or the network interface module 70 may function as one or more of the interface 30-33 of FIG. 1. Note that the IO device interface module 62 and/or the memory interface modules 66-76 may be collectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storage error encoding of data. When a computing device 12 or 16 has data to store it disperse storage error encodes the data in accordance with a dispersed storage error encoding process based on dispersed storage error encoding parameters. The dispersed storage error encoding parameters include an encoding function (e.g., information dispersal algorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding, non-systematic encoding, on-line codes, etc.), a data segmenting protocol (e.g., data segment size, fixed, variable, etc.), and per data segment encoding values. The per data segment encoding values include a total, or pillar width, number (T) of encoded data slices per encoding of a data segment i.e., in a set of encoded data slices); a decode threshold number (D) of encoded data slices of a set of encoded data slices that are needed to recover the data segment; a read threshold number (R) of encoded data slices to indicate a number of encoded data slices per set to be read from storage for decoding of the data segment; and/or a write threshold number (W) to indicate a number of encoded data slices per set that must be accurately stored before the encoded data segment is deemed to have been properly stored. The dispersed storage error encoding parameters may further include slicing information (e.g., the number of encoded data slices that will be created for each data segment) and/or slice security information (e.g., per encoded data slice encryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as the encoding function (a generic example is shown in FIG. 4 and a specific example is shown in FIG. 5); the data segmenting protocol is to divide the data object into fixed sized data segments; and the per data segment encoding values include: a pillar width of 5, a decode threshold of 3, a read threshold of 4, and a write threshold of 4. In accordance with the data segmenting protocol, the computing device 12 or 16 divides the data (e.g., a file (e.g., text, video, audio, etc.), a data object, or other data arrangement) into a plurality of fixed sized data segments (e.g., 1 through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more). The number of data segments created is dependent of the size of the data and the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a data segment using the selected encoding function (e.g., Cauchy Reed-Solomon) to produce a set of encoded data slices. FIG. 4 illustrates a generic Cauchy Reed-Solomon encoding function, which includes an encoding matrix (EM), a data matrix (DM), and a coded matrix (CM). The size of the encoding matrix (EM) is dependent on the pillar width number (T) and the decode threshold number (D) of selected per data segment encoding values. To produce the data matrix (DM), the data segment is divided into a plurality of data blocks and the data blocks are arranged into D number of rows with Z data blocks per row. Note that Z is a function of the number of data blocks created from the data segment and the decode threshold number (D). The coded matrix is produced by matrix multiplying the data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encoding with a pillar number (T) of five and decode threshold number of three. In this example, a first data segment is divided into twelve data blocks (D1-D12). The coded matrix includes five rows of coded data blocks, where the first row of X11-X14 corresponds to a first encoded data slice (EDS 1_1), the second row of X21-X24 corresponds to a second encoded data slice (EDS 2_1), the third row of X31-X34 corresponds to a third encoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to a fourth encoded data slice (EDS 4_1), and the fifth row of X51-X54 corresponds to a fifth encoded data slice (EDS 5_1). Note that the second number of the EDS designation corresponds to the data segment number.

Returning to the discussion of FIG. 3, the computing device also creates a slice name (SN) for each encoded data slice (EDS) in the set of encoded data slices. A typical format for a slice name 60 is shown in FIG. 6. As shown, the slice name (SN) 60 includes a pillar number of the encoded data slice (e.g., one of 1−T), a data segment number (e.g., one of 1−Y), a vault identifier (ID), a data object identifier (ID), and may further include revision level information of the encoded data slices. The slice name functions as, at least part of, a DSN address for the encoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces a plurality of sets of encoded data slices, which are provided with their respective slice names to the storage units for storage. As shown, the first set of encoded data slices includes EDS 1_1 through EDS 5_1 and the first set of slice names includes SN 1_1 through SN 5_1 and the last set of encoded data slices includes EDS 1_Y through EDS 5_Y and the last set of slice names includes SN 1_Y through SN 5 Y.

FIG. 7 is a schematic block diagram of an example of dispersed storage error decoding of a data object that was dispersed storage error encoded and stored in the example of FIG. 4. In this example, the computing device 12 or 16 retrieves from the storage units at least the decode threshold number of encoded data slices per data segment. As a specific example, the computing device retrieves a read threshold number of encoded data slices.

To recover a data segment from a decode threshold number of encoded data slices, the computing device uses a decoding function as shown in FIG. 8. As shown, the decoding function is essentially an inverse of the encoding function of FIG. 4. The coded matrix includes a decode threshold number of rows (e.g., three in this example) and the decoding matrix in an inversion of the encoding matrix that includes the corresponding rows of the coded matrix. For example, if the coded matrix includes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2, and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a schematic block diagram of another embodiment of a dispersed or distributed storage network (DSN) in accordance with the present invention. This diagram includes a schematic block diagram of another embodiment of a dispersed storage network (DSN) that includes one or more storage sets (storage unit (SU) sets) 1-2, the network 24 of FIG. 1, and the distributed storage (DS) client module and/or computing device 16 of FIG. 1. Each storage set includes a set of storage units (SUs) 1−n. Each SU may be implemented utilizing the SU 36 of FIG. 1. The DSN functions to prioritize storage unit utilization, where the one or more storage sets mirror stored data when at least to storage sets are utilized.

In an example of operation of the prioritizing of the storage unit utilization, the DS client module 34 and/or computing device 16 detects slice errors associated with one or more storage units of at least one of the storage sets. For example, the DS client module 34 and/or computing device 16 receives, via the network 24, status information 1−n from the SUs 1−n of the storage set 1, where the status information includes an indication of slice availability by a slice name and revision level, compares the status information to identify a slice errors. The slice errors include one or more of missing slices (e.g., one or more revisions), missing delete markers, and corrupted slices. For instance, the DS client module 34 and/or computing device 16 identifies a missing slice a revision level 3 from SU 2 and identifies a missing delete marker for slice 1 revision level 2 at SU 1. As another example, the DS client module 34 and/or computing device 16 receives, via the network 24, status information set 2 from the storage set 2 and compares the status information set 2 to the status information 1−n from the storage set 1 to identify the slice errors.

Having detected the slice errors, the DS client module 34 and/or computing device 16 updates, for each SU and each storage set, a usage priority level based on the detecting slice errors. For example, the DS client module 34 and/or computing device 16 lowers the priority when detecting an error and raises the priority when no errors are detected. When accessing data in one of the storage sets, the DS client module 34 and/or computing device 16 selects one storage set based on the usage priority level of each of the storage sets to produce a selected storage set. For example, the DS client module 34 and/or computing device 16 selects a storage set associated with a more favorable usage priority level (e.g., higher-level).

For the selected storage set, the DS client module 34 and/or computing device 16 selects a threshold number of SUs of the set of SUs based on the usage priority level for each of the SUs. For example, when writing data, the DS client module 34 and/or computing device 16 selects a write threshold number with a more favorable usage priority level. As another example, when reading store data, the DS client module 34 and/or computing device 16 selects a read threshold number with a more favorable usage priority level. Having selected the threshold number of SUs, the DS client module 34 and/or computing device 16 facilitates execution of the accessing of the data utilizing the selected threshold number of SUs. For example, the DS client module 34 and/or computing device 16 issues, via the network 24, access requests to the selected SUs of the storage set 1 and receives access responses from at least some of the selected SUs.

In some examples, note that dispersed or distributed storage network (DSN) memory includes one or more of a plurality of storage units (SUs) such as SUs 36 (e.g., that may alternatively be referred to a distributed storage and/or task network (DSTN) module that includes a plurality of distributed storage and/or task (DST) execution units 36 that may be located at geographically different sites (e.g., one in Chicago, one in Milwaukee, etc.). Each of the SUs (e.g., alternatively referred to as DST execution units in some examples) is operable to store dispersed error encoded data and/or to execute, in a distributed manner, one or more tasks on data. The tasks may be a simple function (e.g., a mathematical function, a logic function, an identify function, a find function, a search engine function, a replace function, etc.), a complex function (e.g., compression, human and/or computer language translation, text-to-voice conversion, voice-to-text conversion, etc.), multiple simple and/or complex functions, one or more algorithms, one or more applications, etc.

In an example of operation and implementation, a computing device includes an interface configured to interface and communicate with a dispersed or distributed storage network (DSN), a memory that stores operational instructions, and a processing module, processor, and/or processing circuitry operably coupled to the interface and memory. The processing module, processor, and/or processing circuitry is configured to execute the operational instructions to perform various operations, functions, etc. In some examples, the processing module, processor, and/or processing circuitry, when operable within the computing device based on the operational instructions, is configured to perform various operations, functions, etc. In certain examples, the processing module, processor, and/or processing circuitry, when operable within the computing device is configured to perform one or more functions that may include generation of one or more signals, processing of one or more signals, receiving of one or more signals, transmission of one or more signals, interpreting of one or more signals, etc. and/or any other operations as described herein and/or their equivalents.

In an example of operation and implementation, the DS client module 34 and/or computing device 16 is configured to identify one or more slice errors associated with first one or more storage units (SUs) of a first storage set that distributedly store a set of encoded data slices (EDSs) associated with a data object and second one or more SUs of a second storage set. Note that the data object is segmented into a plurality of data segments, and a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs. Also, a decode threshold number of EDSs are needed to recover the data segment. The DS client module 34 and/or computing device 16 is also configured to determine one or more usage priority levels of the first one or more SUs of the first storage set and/or the second one or more SUs of the second storage set based on the one or more slice errors that are detected. In some examples, at least one of the second one or more SUs of the second storage set also stores at least one EDS of the set of EDSs (e.g., such as in accordance with a mirrored storage of the at least one EDS of the set of EDSs). The DS client module 34 and/or computing device 16 is also configured to produce a selected storage set from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set based on a more favorable usage priority level of the one or more usage priority levels of the at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set. Then, the DS client module 34 and/or computing device 16 is configured to facilitate execution of data access to at least the decode threshold number of EDSs based on the selected storage set.

Also, in some examples, the DS client module 34 and/or computing device 16 is configured to produce the selected storage set that includes a read threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a read data access. For example, a read threshold number of EDSs provides for reconstruction of the data segment.

In even other examples, the DS client module 34 and/or computing device 16 is configured to produce the selected storage set that includes a write threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a write data access. For example, a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN.

Also, in yet other examples, the DS client module 34 and/or computing device 16 is configured to receive status information associated with the first one or more SUs of the first SU set, wherein the status information includes an indication of EDS availability by a slice name and a revision level. The DS client module 34 and/or computing device 16 is also configured to compare the status information to identify the one or more slice errors, wherein the one or more slice errors includes a missing EDS, a missing delete marker, and/or a corrupted EDS.

In some examples, with respect to a data object, the data object is segmented into a plurality of data segments, and a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce a set of encoded data slices (EDSs) (e.g., in some instances, the set of EDSs are distributedly stored in a plurality of storage units (SUs) within the DSN). In some examples, the set of EDSs is of pillar width. Also, with respect to certain implementations, note that the decode threshold number of EDSs are needed to recover the data segment, and a read threshold number of EDSs provides for reconstruction of the data segment. Also, a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN. The set of EDSs is of pillar width and includes a pillar number of EDSs. Also, in some examples, each of the decode threshold, the read threshold, and the write threshold is less than the pillar number. Also, in some particular examples, the write threshold number is greater than or equal to the read threshold number that is greater than or equal to the decode threshold number.

Note that the computing device as described herein may be is located at a first premises that is remotely located from a second premises of at least one SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN. For example, in some examples, the computing device as described herein may be located at a first premises that is remotely located from a second premises associated with at least one other SU, DS unit, computing device, at least one SU of a plurality of SUs within the DSN (e.g., such as a plurality of SUs that are implemented to store distributedly the set of EDSs), etc. In addition, note that such a computing device as described herein may be implemented as any of a number of different devices including a managing unit that is remotely located from another SU, DS unit, computing device, etc. within the DSN and/or other device within the DSN, an integrity processing unit that is remotely located from another computing device and/or other device within the DSN, a scheduling unit that is remotely located from another computing device and/or SU within the DSN, and/or other device. Also, note that such a computing device as described herein may be of any of a variety of types of devices as described herein and/or their equivalents including a DS unit and/or SU included within any group and/or set of DS units and/or SUs within the DSN, a SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, and/or a video game device. Also, note also that the DSN may be implemented to include or be based on any of a number of different types of communication systems including a wireless communication system, a wire lined communication system, a non-public intranet system, a public internet system, a local area network (LAN), and/or a wide area network (WAN).

FIG. 10 is a flowchart illustrating an example of prioritizing storage unit utilization in accordance with the present invention. This diagram includes a flowchart illustrating an example of prioritizing storage unit utilization. The method 1000 begins or continues at a step 1010 where a processing module (e.g., of a distributed storage (DS) client module and/or computing device) detects a slice error associated with a storage unit of a storage set of two or more affiliated storage sets, where the two or more affiliated storage sets may mirror stored data as substantially identical sets of encoded data slices. For example, the processing module obtains slice status information from storage units of the two or more affiliated storage sets, compares the status information, and identifies a storage anomaly (e.g., a missing slice, a corrupted slice) to produce the slice error.

The method 1000 continues at the step 1020 where the processing module updates a usage priority level associated with the storage unit and a usage priority level associated with the storage set. For example, the processing module maintains or raises the level when not detecting the slice error. As another example, the processing module lowers the level when detecting the slice error.

When accessing data in one of the two or more affiliated storage sets, the method 1000 continues at the step 1030 where the processing module selects the one storage set based on usage priority level. For example, the processing module selects a storage set associated with a more favorable usage priority level (e.g., a higher-level). For the selected storage set, the method 1000 continues at the step 1040 where the processing module selects a threshold number of storage units based on the usage priority levels for each of the storage units of the selected storage set. For example, the processing module selects a write threshold number associated with a more favorable usage priority level when writing data. As another example, the processing module selects a read threshold number associated with a more favorable usage priority level when reading data.

The method 1000 continues at the step 1050 where the processing module facilitates execution of accessing of the data utilizing the selected threshold number of storage units of the selected storage set. For example, the processing module issues access requests to the selected storage units of the selected storage set, receives access responses from at least some of the selected storage units of the selected storage set, and processes the received access responses to produce an overall access response (e.g., output data when reading, indicate storage of data and when storing the data).

FIG. 11 is a diagram illustrating an embodiment of a method 1100 for execution by one or more computing devices in accordance with the present invention. The method 1100 operates in step 1110 by identifying one or more slice errors associated with first one or more storage units (SUs) of a first storage set within a dispersed or distributed storage network (DSN) that distributedly store a set of encoded data slices (EDSs) associated with a data object and second one or more SUs of a second storage set within the DSN. In some examples, the data object is segmented into a plurality of data segments, and a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs. Also, a decode threshold number of EDSs are needed to recover the data segment;

The method 1100 then continues in step 1120 by determining one or more usage priority levels of at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set based on the one or more slice errors that are detected, wherein at least one of the second one or more SUs of the second storage set also stores at least one EDS of the set of EDSs. The method 1100 operates in step 1130 by producing a selected storage set from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set based on a more favorable usage priority level of the one or more usage priority levels of the at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set. The method 1100 then continues in step 1140 by facilitating (e.g., via an interface of the computing device that is configured to interface and communicate with the DSN) execution of data access to at least the decode threshold number of EDSs based on the selected storage set.

This disclosure presents, among other things, various novel solutions that facilitate improved operation of a data storage system in the case of memory device failures, network outages, and/or other situations that may adversely affect performance of the data storage system. For example, errors may be induced in cases of memory device failures, or network outages of sites, or SUs. A computing device, DS module, and/or DS processing unit that does not take into account success rate of requests sent to SUs with a high historical probability of returning an error or source not found for a namespace range, a memory device, or a set of sources for the same object, may make the error of giving the SU a higher priority owing to the speedy response. However, when the response is not in accordance with the threshold (or majority) of the responding SUs, this should lower the ranking of that SU, for a particular range of the SU such as the one covering the memory device the request was mapped to, and/or the segments of the requested source. For example, when responding to a request and some SUs return data while most other SUs return a delete marker, the SUs that returned the data are outdated, and should suffer a reduced priority for returning an errant response. Likewise, when one or more SUs return data not found errors, delete markers, stale revisions, or other indications of error while the rest of the SUs return valid data of a different agreed upon revision, then the SUs which strayed from the agreed upon set of slices returned will similarly suffer a reduced priority for future requests. This same strategy may be applied more generally when there are replication sets for the same vault, e.g. when there are two vaults which are in a replication group, and one set of SUs at one site consistently has an older revision or lacks the data entirely, then SUs at that site may have their priority reduced, such that the SU which more consistently returns the most recent revision is checked more frequently.

It is noted that terminologies as may be used herein such as bit stream, stream, signal sequence, etc. (or their equivalents) have been used interchangeably to describe digital information whose content corresponds to any of a number of desired types (e.g., data, video, speech, audio, etc. any of which may generally be referred to as ‘data’).

As may be used herein, the terms “substantially” and “approximately” provides an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to fifty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. Such relativity between items ranges from a difference of a few percent to magnitude differences. As may also be used herein, the term(s) “configured to”, “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for an example of indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. As may even further be used herein, the term “configured to”, “operable to”, “coupled to”, or “operably coupled to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform, when activated, one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater magnitude than signal 2, a favorable comparison may be achieved when the magnitude of signal 1 is greater than that of signal 2 or when the magnitude of signal 2 is less than that of signal 1. As may be used herein, the term “compares unfavorably”, indicates that a comparison between two or more items, signals, etc., fails to provide the desired relationship.

As may also be used herein, the terms “processing module”, “processing circuit”, “processor”, and/or “processing unit” may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module, module, processing circuit, and/or processing unit may be, or further include, memory and/or an integrated memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of another processing module, module, processing circuit, and/or processing unit. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, module, processing circuit, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that if the processing module, module, processing circuit, and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element may store, and the processing module, module, processing circuit, and/or processing unit executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the figures. Such a memory device or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claims. Further, the boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claims. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof.

In addition, a flow diagram may include a “start” and/or “continue” indication. The “start” and “continue” indications reflect that the steps presented can optionally be incorporated in or otherwise used in conjunction with other routines. In this context, “start” indicates the beginning of the first step presented and may be preceded by other activities not specifically shown. Further, the “continue” indication reflects that the steps presented may be performed multiple times and/or may be succeeded by other activities not specifically shown. Further, while a flow diagram indicates a particular ordering of steps, other orderings are likewise possible provided that the principles of causality are maintained.

The one or more embodiments are used herein to illustrate one or more aspects, one or more features, one or more concepts, and/or one or more examples. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones.

Unless specifically stated to the contra, signals to, from, and/or between elements in a figure of any of the figures presented herein may be analog or digital, continuous time or discrete time, and single-ended or differential. For instance, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more particular architectures are described herein, other architectures can likewise be implemented that use one or more data buses not expressly shown, direct connectivity between elements, and/or indirect coupling between other elements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of the embodiments. A module implements one or more functions via a device such as a processor or other processing device or other hardware that may include or operate in association with a memory that stores operational instructions. A module may operate independently and/or in conjunction with software and/or firmware. As also used herein, a module may contain one or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes one or more memory elements. A memory element may be a separate memory device, multiple memory devices, or a set of memory locations within a memory device. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. The memory device may be in a form a solid state memory, a hard drive memory, cloud memory, thumb drive, server memory, computing device memory, and/or other physical medium for storing digital information.

While particular combinations of various functions and features of the one or more embodiments have been expressly described herein, other combinations of these features and functions are likewise possible. The present disclosure is not limited by the particular examples disclosed herein and expressly incorporates these other combinations. 

What is claimed is:
 1. A computing device comprising: an interface configured to interface and communicate with a dispersed or distributed storage network (DSN); memory that stores operational instructions; and processing circuitry operably coupled to the interface and to the memory, wherein the processing circuitry is configured to execute the operational instructions to: identify one or more slice errors associated with first one or more storage units (SUs) of a first storage set that distributedly store a set of encoded data slices (EDSs) associated with a data object and second one or more SUs of a second storage set, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs, wherein a decode threshold number of EDSs are needed to recover the data segment; determine one or more usage priority levels of at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set based on the one or more slice errors that are detected, wherein at least one of the second one or more SUs of the second storage set also stores at least one EDS of the set of EDSs; produce a selected storage set from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set based on a more favorable usage priority level of the one or more usage priority levels of the at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set; and facilitate execution of data access to at least the decode threshold number of EDSs based on the selected storage set.
 2. The computing device of claim 1, wherein the processing circuitry is further configured to execute the operational instructions to: produce the selected storage set that includes a read threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a read data access, wherein a read threshold number of EDSs provides for reconstruction of the data segment.
 3. The computing device of claim 1, wherein the processing circuitry is further configured to execute the operational instructions to: produce the selected storage set that includes a write threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a write data access, wherein a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN.
 4. The computing device of claim 1, wherein the processing circuitry is further configured to execute the operational instructions to: receive status information associated with the first one or more SUs of the first SU set, wherein the status information includes an indication of EDS availability by a slice name and a revision level; and compare the status information to identify the one or more slice errors, wherein the one or more slice errors includes at least one of a missing EDS, a missing delete marker, or a corrupted EDS.
 5. The computing device of claim 1, wherein: a read threshold number of EDSs provides for reconstruction of the data segment; a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN; the set of EDSs is of pillar width and includes a pillar number of EDSs; each of the decode threshold number, the read threshold number, and the write threshold number is less than the pillar number; and the write threshold number is greater than or equal to the read threshold number that is greater than or equal to the decode threshold number.
 6. The computing device of claim 1, wherein the computing device is located at a first premises that is remotely located from a second premises of at least one SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN.
 7. The computing device of claim 1 further comprising: a SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device.
 8. The computing device of claim 1, wherein the DSN includes at least one of a wireless communication system, a wire lined communication system, a non-public intranet system, a public internet system, a local area network (LAN), or a wide area network (WAN).
 9. A computing device comprising: an interface configured to interface and communicate with a dispersed or distributed storage network (DSN); memory that stores operational instructions; and processing circuitry operably coupled to the interface and to the memory, wherein the processing circuitry is configured to execute the operational instructions to: identify one or more slice errors associated with first one or more storage units (SUs) of a first storage set that distributedly store a set of encoded data slices (EDSs) associated with a data object and second one or more SUs of a second storage set, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs, wherein a decode threshold number of EDSs are needed to recover the data segment; determine one or more usage priority levels of at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set based on the one or more slice errors that are detected, wherein at least one of the second one or more SUs of the second storage set also stores at least one EDS of the set of EDSs; produce a selected storage set from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set based on a more favorable usage priority level of the one or more usage priority levels of the at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set including to: produce the selected storage set that includes a read threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a read data access, wherein a read threshold number of EDSs provides for reconstruction of the data segment; and produce the selected storage set that includes a write threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a write data access, wherein a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN; and facilitate execution of data access to at least one of the decode threshold number of EDSs, read threshold number of EDSs, or the write threshold number of EDSs based on the selected storage set.
 10. The computing device of claim 9, wherein the processing circuitry is further configured to execute the operational instructions to: receive status information associated with the first one or more SUs of the first SU set, wherein the status information includes an indication of EDS availability by a slice name and a revision level; and compare the status information to identify the one or more slice errors, wherein the one or more slice errors includes at least one of a missing EDS, a missing delete marker, or a corrupted EDS.
 11. The computing device of claim 9, wherein: the set of EDSs is of pillar width and includes a pillar number of EDSs; each of the decode threshold number, the read threshold number, and the write threshold number is less than the pillar number; and the write threshold number is greater than or equal to the read threshold number that is greater than or equal to the decode threshold number.
 12. The computing device of claim 9 further comprising: a SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device.
 13. The computing device of claim 9, wherein the DSN includes at least one of a wireless communication system, a wire lined communication system, a non-public intranet system, a public internet system, a local area network (LAN), or a wide area network (WAN).
 14. A method for execution by a computing device, the method comprising: identifying one or more slice errors associated with first one or more storage units (SUs) of a first storage set within a dispersed or distributed storage network (DSN) that distributedly store a set of encoded data slices (EDSs) associated with a data object and second one or more SUs of a second storage set within the DSN, wherein the data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs, wherein a decode threshold number of EDSs are needed to recover the data segment; determining one or more usage priority levels of at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set based on the one or more slice errors that are detected, wherein at least one of the second one or more SUs of the second storage set also stores at least one EDS of the set of EDSs; producing a selected storage set from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set based on a more favorable usage priority level of the one or more usage priority levels of the at least one of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set; and facilitating, via an interface of the computing device that is configured to interface and communicate with the DSN, execution of data access to at least the decode threshold number of EDSs based on the selected storage set.
 15. The method of claim 14 further comprising: producing the selected storage set that includes a read threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a read data access, wherein a read threshold number of EDSs provides for reconstruction of the data segment.
 16. The method of claim 14 further comprising: producing the selected storage set that includes a write threshold number of SUs having the more favorable usage priority level from the first one or more SUs of the first storage set and the second one or more SUs of the second storage set when facilitation execution of a write data access, wherein a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN.
 17. The method of claim 14 further comprising: receiving status information associated with the first one or more SUs of the first SU set, wherein the status information includes an indication of EDS availability by a slice name and a revision level; and comparing the status information to identify the one or more slice errors, wherein the one or more slice errors includes at least one of a missing EDS, a missing delete marker, or a corrupted EDS.
 18. The method of claim 14, wherein: a read threshold number of EDSs provides for reconstruction of the data segment; a write threshold number of EDSs provides for a successful transfer of the set of EDSs from a first at least one location in the DSN to a second at least one location in the DSN; the set of EDSs is of pillar width and includes a pillar number of EDSs; each of the decode threshold number, the read threshold number, and the write threshold number is less than the pillar number; and the write threshold number is greater than or equal to the read threshold number that is greater than or equal to the decode threshold number.
 19. The method of claim 14, wherein the computing device includes a SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device.
 20. The method of claim 14, a SU of the first one or more SUs of the first storage set or the second one or more SUs of the second storage set within the DSN, a wireless smart phone, a laptop, a tablet, a personal computers (PC), a work station, or a video game device. 